A PPP blood test refers to the preparation of Platelet-Poor Plasma (PPP), which is blood plasma that has been processed to significantly reduce the number of platelets it contains (typically less than 10 x 10^3/μL).
Purpose of Preparing PPP
PPP is primarily prepared for use in coagulation or platelet function testing. Its main uses include:
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Adjusting Platelet-Rich Plasma (PRP) concentration: When performing platelet aggregation studies, PPP can be used to dilute PRP to achieve the desired platelet concentration.
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Serving as a Control: In platelet aggregation assays, PPP serves as a blank or control to ensure accurate measurement of platelet activity. This helps differentiate between true platelet aggregation and background interference.
How PPP is Prepared
PPP is typically obtained through a process of centrifugation:
- A blood sample is collected in a tube containing an anticoagulant (e.g., citrate).
- The sample is centrifuged at a specific speed and time to separate the blood components. The centrifugation parameters are designed to pellet the red blood cells and platelets, leaving the plasma on top.
- The plasma is carefully removed and subjected to a second centrifugation step at a higher speed or longer time to further reduce the platelet count.
- The resulting supernatant is the PPP.
Why Low Platelet Count is Important
Maintaining a very low platelet count in PPP is crucial for accurate testing. Any residual platelets can interfere with the results of platelet aggregation studies, leading to misinterpretations.
